Role of food intake on the Hypothalamo-Pituitary-Adrenal function during insulinginduced hypoglicemia.

A. GIOVAMBATTISTA, A. CHISARI, J. PIERMARIA AND E. SPINEDI.

San Diego, USA

Congreso; Annual Meeting of the American Endocrine Society; 1999

American Endocrine Society

ROLE OF FOOD INTAKE ON THE HYPOTHALAMO-PITUITARY-ADRENAL (HPA) AXIS FUNCIION DURING INSULIN.INDUCED HYPOGLYCEMIA.   A. Giovambattista1,2, A N Chisari1,2, J Piermaria1, E. Spinedi1. 1Neuroendocrine Unit, IMBICE -  2UNLP, La Plata, Argentina The aim of the present estudy was to determine the role played by food intake on HPA axis function after insulin administration (INS) in adult female BAIB/c mice. Our experi­mental design included 24-hours fasted mice-injected (i.p.) with either sterile saline solution alone (VEH; 50 ml) or containing INS (0.3 IU/mouse). Immediately after treatment, VEH-injected mice were killed by decapitation (sample time zero). Remaining animals were back to their home cages and allowcd to normal diet chow available ad libitum; animais were then killed 15, 30 and 45 min after either treatment (n = 6-8 mice per time/treatment). Trunk blood was collected into plastic Eppendorf tubes containing EDTA/sodium fluoride. Plasma samples were immediately split in aliquota and frozen (-20 C) until measurement of glucose (GLU; enzymatic assay), ACTH (IRMA), corticosterone (RIA) and leptin (LEP; RIA) concentrations. The results indicate that: a) whereas hyperglycemia was found (P<0.05 vs. time zero values) 15, 30 and 45 mm after VEH injection, a significant hypoglycemia (P<0.05 vs. time zero values) was induced 15 and 30 min alter INS administration, however, 45 min after INS treatment, plasma GLU concen­trations were back to the respective sample time zero values; b) no significant increase, vs. time zero values, in plasma ACTH concentrations were found at any time studied in both experimental groups; c) the basal (time 0) hypercorticosteronemia, induced by 24-hours of fasting, was significantly (P<0.05) decreased 45 min after VEH or INS treatment; and d) although no significant differences between groups in plasma LEP values were found 0, 15 and 3Omin afler treatments, circulating LEP was signiflcantly (P<0.05) higher 45 min after injeclion of INS than after VEH treatment. These results clearly indicate that: 1) hypoglycemia by itself is not fully responsible for the enhance in HPA axis function after INS administration, and 2) food intake, combined with an increase in circulating LEP, reversed fasting-induced basal hypercorticosteronemia and abolished HPA axis response after INS-induced hypoglycemia. (Supported by grants from CONICET, CIC and UNLP, Argentina).